fs/erofs/zdata.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2018 HUAWEI, Inc.
   4  *             https://www.huawei.com/
   5  */
   6 #include "zdata.h"
   7 #include "compress.h"
   8 #include <linux/prefetch.h>
   9
  10 #include <trace/events/erofs.h>
  11
  12 /*
  13  * since pclustersize is variable for big pcluster feature, introduce slab
  14  * pools implementation for different pcluster sizes.
  15  */
  16 struct z_erofs_pcluster_slab {
  17         struct kmem_cache *slab;
  18         unsigned int maxpages;
  19         char name[48];
  20 };
  21
  22 #define _PCLP(n) { .maxpages = n }
  23
  24 static struct z_erofs_pcluster_slab pcluster_pool[] __read_mostly = {
  25         _PCLP(1), _PCLP(4), _PCLP(16), _PCLP(64), _PCLP(128),
  26         _PCLP(Z_EROFS_PCLUSTER_MAX_PAGES)
  27 };
  28
  29 static void z_erofs_destroy_pcluster_pool(void)
  30 {
  31         int i;
  32
  33         for (i = 0; i < ARRAY_SIZE(pcluster_pool); ++i) {
  34                 if (!pcluster_pool[i].slab)
  35                         continue;
  36                 kmem_cache_destroy(pcluster_pool[i].slab);
  37                 pcluster_pool[i].slab = NULL;
  38         }
  39 }
  40
  41 static int z_erofs_create_pcluster_pool(void)
  42 {
  43         struct z_erofs_pcluster_slab *pcs;
  44         struct z_erofs_pcluster *a;
  45         unsigned int size;
  46
  47         for (pcs = pcluster_pool;
  48              pcs < pcluster_pool + ARRAY_SIZE(pcluster_pool); ++pcs) {
  49                 size = struct_size(a, compressed_pages, pcs->maxpages);
  50
  51                 sprintf(pcs->name, "erofs_pcluster-%u", pcs->maxpages);
  52                 pcs->slab = kmem_cache_create(pcs->name, size, 0,
  53                                               SLAB_RECLAIM_ACCOUNT, NULL);
  54                 if (pcs->slab)
  55                         continue;
  56
  57                 z_erofs_destroy_pcluster_pool();
  58                 return -ENOMEM;
  59         }
  60         return 0;
  61 }
  62
  63 static struct z_erofs_pcluster *z_erofs_alloc_pcluster(unsigned int nrpages)
  64 {
  65         int i;
  66
  67         for (i = 0; i < ARRAY_SIZE(pcluster_pool); ++i) {
  68                 struct z_erofs_pcluster_slab *pcs = pcluster_pool + i;
  69                 struct z_erofs_pcluster *pcl;
  70
  71                 if (nrpages > pcs->maxpages)
  72                         continue;
  73
  74                 pcl = kmem_cache_zalloc(pcs->slab, GFP_NOFS);
  75                 if (!pcl)
  76                         return ERR_PTR(-ENOMEM);
  77                 pcl->pclusterpages = nrpages;
  78                 return pcl;
  79         }
  80         return ERR_PTR(-EINVAL);
  81 }
  82
  83 static void z_erofs_free_pcluster(struct z_erofs_pcluster *pcl)
  84 {
  85         int i;
  86
  87         for (i = 0; i < ARRAY_SIZE(pcluster_pool); ++i) {
  88                 struct z_erofs_pcluster_slab *pcs = pcluster_pool + i;
  89
  90                 if (pcl->pclusterpages > pcs->maxpages)
  91                         continue;
  92
  93                 kmem_cache_free(pcs->slab, pcl);
  94                 return;
  95         }
  96         DBG_BUGON(1);
  97 }
  98
  99 /*
 100  * a compressed_pages[] placeholder in order to avoid
 101  * being filled with file pages for in-place decompression.
 102  */
 103 #define PAGE_UNALLOCATED     ((void *)0x5F0E4B1D)
 104
 105 /* how to allocate cached pages for a pcluster */
 106 enum z_erofs_cache_alloctype {
 107         DONTALLOC,      /* don't allocate any cached pages */
 108         DELAYEDALLOC,   /* delayed allocation (at the time of submitting io) */
 109         /*
 110          * try to use cached I/O if page allocation succeeds or fallback
 111          * to in-place I/O instead to avoid any direct reclaim.
 112          */
 113         TRYALLOC,
 114 };
 115
 116 /*
 117  * tagged pointer with 1-bit tag for all compressed pages
 118  * tag 0 - the page is just found with an extra page reference
 119  */
 120 typedef tagptr1_t compressed_page_t;
 121
 122 #define tag_compressed_page_justfound(page) \
 123         tagptr_fold(compressed_page_t, page, 1)
 124
 125 static struct workqueue_struct *z_erofs_workqueue __read_mostly;
 126
 127 void z_erofs_exit_zip_subsystem(void)
 128 {
 129         destroy_workqueue(z_erofs_workqueue);
 130         z_erofs_destroy_pcluster_pool();
 131 }
 132
 133 static inline int z_erofs_init_workqueue(void)
 134 {
 135         const unsigned int onlinecpus = num_possible_cpus();
 136
 137         /*
 138          * no need to spawn too many threads, limiting threads could minimum
 139          * scheduling overhead, perhaps per-CPU threads should be better?
 140          */
 141         z_erofs_workqueue = alloc_workqueue("erofs_unzipd",
 142                                             WQ_UNBOUND | WQ_HIGHPRI,
 143                                             onlinecpus + onlinecpus / 4);
 144         return z_erofs_workqueue ? 0 : -ENOMEM;
 145 }
 146
 147 int __init z_erofs_init_zip_subsystem(void)
 148 {
 149         int err = z_erofs_create_pcluster_pool();
 150
 151         if (err)
 152                 return err;
 153         err = z_erofs_init_workqueue();
 154         if (err)
 155                 z_erofs_destroy_pcluster_pool();
 156         return err;
 157 }
 158
 159 enum z_erofs_collectmode {
 160         COLLECT_SECONDARY,
 161         COLLECT_PRIMARY,
 162         /*
 163          * The current collection was the tail of an exist chain, in addition
 164          * that the previous processed chained collections are all decided to
 165          * be hooked up to it.
 166          * A new chain will be created for the remaining collections which are
 167          * not processed yet, therefore different from COLLECT_PRIMARY_FOLLOWED,
 168          * the next collection cannot reuse the whole page safely in
 169          * the following scenario:
 170          *  ________________________________________________________________
 171          * |      tail (partial) page     |       head (partial) page       |
 172          * |   (belongs to the next cl)   |   (belongs to the current cl)   |
 173          * |_______PRIMARY_FOLLOWED_______|________PRIMARY_HOOKED___________|
 174          */
 175         COLLECT_PRIMARY_HOOKED,
 176         /*
 177          * a weak form of COLLECT_PRIMARY_FOLLOWED, the difference is that it
 178          * could be dispatched into bypass queue later due to uptodated managed
 179          * pages. All related online pages cannot be reused for inplace I/O (or
 180          * pagevec) since it can be directly decoded without I/O submission.
 181          */
 182         COLLECT_PRIMARY_FOLLOWED_NOINPLACE,
 183         /*
 184          * The current collection has been linked with the owned chain, and
 185          * could also be linked with the remaining collections, which means
 186          * if the processing page is the tail page of the collection, thus
 187          * the current collection can safely use the whole page (since
 188          * the previous collection is under control) for in-place I/O, as
 189          * illustrated below:
 190          *  ________________________________________________________________
 191          * |  tail (partial) page |          head (partial) page           |
 192          * |  (of the current cl) |      (of the previous collection)      |
 193          * |  PRIMARY_FOLLOWED or |                                        |
 194          * |_____PRIMARY_HOOKED___|____________PRIMARY_FOLLOWED____________|
 195          *
 196          * [  (*) the above page can be used as inplace I/O.               ]
 197          */
 198         COLLECT_PRIMARY_FOLLOWED,
 199 };
 200
 201 struct z_erofs_collector {
 202         struct z_erofs_pagevec_ctor vector;
 203
 204         struct z_erofs_pcluster *pcl, *tailpcl;
 205         struct z_erofs_collection *cl;
 206         /* a pointer used to pick up inplace I/O pages */
 207         struct page **icpage_ptr;
 208         z_erofs_next_pcluster_t owned_head;
 209
 210         enum z_erofs_collectmode mode;
 211 };
 212
 213 struct z_erofs_decompress_frontend {
 214         struct inode *const inode;
 215
 216         struct z_erofs_collector clt;
 217         struct erofs_map_blocks map;
 218
 219         bool readahead;
 220         /* used for applying cache strategy on the fly */
 221         bool backmost;
 222         erofs_off_t headoffset;
 223 };
 224
 225 #define COLLECTOR_INIT() { \
 226         .owned_head = Z_EROFS_PCLUSTER_TAIL, \
 227         .mode = COLLECT_PRIMARY_FOLLOWED }
 228
 229 #define DECOMPRESS_FRONTEND_INIT(__i) { \
 230         .inode = __i, .clt = COLLECTOR_INIT(), \
 231         .backmost = true, }
 232
 233 static struct page *z_pagemap_global[Z_EROFS_VMAP_GLOBAL_PAGES];
 234 static DEFINE_MUTEX(z_pagemap_global_lock);
 235
 236 static void preload_compressed_pages(struct z_erofs_collector *clt,
 237                                      struct address_space *mc,
 238                                      enum z_erofs_cache_alloctype type,
 239                                      struct list_head *pagepool)
 240 {
 241         struct z_erofs_pcluster *pcl = clt->pcl;
 242         bool standalone = true;
 243         gfp_t gfp = (mapping_gfp_mask(mc) & ~__GFP_DIRECT_RECLAIM) |
 244                         __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
 245         struct page **pages;
 246         pgoff_t index;
 247
 248         if (clt->mode < COLLECT_PRIMARY_FOLLOWED)
 249                 return;
 250
 251         pages = pcl->compressed_pages;
 252         index = pcl->obj.index;
 253         for (; index < pcl->obj.index + pcl->pclusterpages; ++index, ++pages) {
 254                 struct page *page;
 255                 compressed_page_t t;
 256                 struct page *newpage = NULL;
 257
 258                 /* the compressed page was loaded before */
 259                 if (READ_ONCE(*pages))
 260                         continue;
 261
 262                 page = find_get_page(mc, index);
 263
 264                 if (page) {
 265                         t = tag_compressed_page_justfound(page);
 266                 } else {
 267                         /* I/O is needed, no possible to decompress directly */
 268                         standalone = false;
 269                         switch (type) {
 270                         case DELAYEDALLOC:
 271                                 t = tagptr_init(compressed_page_t,
 272                                                 PAGE_UNALLOCATED);
 273                                 break;
 274                         case TRYALLOC:
 275                                 newpage = erofs_allocpage(pagepool, gfp);
 276                                 if (!newpage)
 277                                         continue;
 278                                 set_page_private(newpage,
 279                                                  Z_EROFS_PREALLOCATED_PAGE);
 280                                 t = tag_compressed_page_justfound(newpage);
 281                                 break;
 282                         default:        /* DONTALLOC */
 283                                 continue;
 284                         }
 285                 }
 286
 287                 if (!cmpxchg_relaxed(pages, NULL, tagptr_cast_ptr(t)))
 288                         continue;
 289
 290                 if (page) {
 291                         put_page(page);
 292                 } else if (newpage) {
 293                         set_page_private(newpage, 0);
 294                         list_add(&newpage->lru, pagepool);
 295                 }
 296         }
 297
 298         /*
 299          * don't do inplace I/O if all compressed pages are available in
 300          * managed cache since it can be moved to the bypass queue instead.
 301          */
 302         if (standalone)
 303                 clt->mode = COLLECT_PRIMARY_FOLLOWED_NOINPLACE;
 304 }
 305
 306 /* called by erofs_shrinker to get rid of all compressed_pages */
 307 int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
 308                                        struct erofs_workgroup *grp)
 309 {
 310         struct z_erofs_pcluster *const pcl =
 311                 container_of(grp, struct z_erofs_pcluster, obj);
 312         struct address_space *const mapping = MNGD_MAPPING(sbi);
 313         int i;
 314
 315         /*
 316          * refcount of workgroup is now freezed as 1,
 317          * therefore no need to worry about available decompression users.
 318          */
 319         for (i = 0; i < pcl->pclusterpages; ++i) {
 320                 struct page *page = pcl->compressed_pages[i];
 321
 322                 if (!page)
 323                         continue;
 324
 325                 /* block other users from reclaiming or migrating the page */
 326                 if (!trylock_page(page))
 327                         return -EBUSY;
 328
 329                 if (page->mapping != mapping)
 330                         continue;
 331
 332                 /* barrier is implied in the following 'unlock_page' */
 333                 WRITE_ONCE(pcl->compressed_pages[i], NULL);
 334                 detach_page_private(page);
 335                 unlock_page(page);
 336         }
 337         return 0;
 338 }
 339
 340 int erofs_try_to_free_cached_page(struct address_space *mapping,
 341                                   struct page *page)
 342 {
 343         struct z_erofs_pcluster *const pcl = (void *)page_private(page);
 344         int ret = 0;    /* 0 - busy */
 345
 346         if (erofs_workgroup_try_to_freeze(&pcl->obj, 1)) {
 347                 unsigned int i;
 348
 349                 for (i = 0; i < pcl->pclusterpages; ++i) {
 350                         if (pcl->compressed_pages[i] == page) {
 351                                 WRITE_ONCE(pcl->compressed_pages[i], NULL);
 352                                 ret = 1;
 353                                 break;
 354                         }
 355                 }
 356                 erofs_workgroup_unfreeze(&pcl->obj, 1);
 357
 358                 if (ret)
 359                         detach_page_private(page);
 360         }
 361         return ret;
 362 }
 363
 364 /* page_type must be Z_EROFS_PAGE_TYPE_EXCLUSIVE */
 365 static bool z_erofs_try_inplace_io(struct z_erofs_collector *clt,
 366                                    struct page *page)
 367 {
 368         struct z_erofs_pcluster *const pcl = clt->pcl;
 369
 370         while (clt->icpage_ptr > pcl->compressed_pages)
 371                 if (!cmpxchg(--clt->icpage_ptr, NULL, page))
 372                         return true;
 373         return false;
 374 }
 375
 376 /* callers must be with collection lock held */
 377 static int z_erofs_attach_page(struct z_erofs_collector *clt,
 378                                struct page *page,
 379                                enum z_erofs_page_type type)
 380 {
 381         int ret;
 382
 383         /* give priority for inplaceio */
 384         if (clt->mode >= COLLECT_PRIMARY &&
 385             type == Z_EROFS_PAGE_TYPE_EXCLUSIVE &&
 386             z_erofs_try_inplace_io(clt, page))
 387                 return 0;
 388
 389         ret = z_erofs_pagevec_enqueue(&clt->vector, page, type);
 390         clt->cl->vcnt += (unsigned int)ret;
 391
 392         return ret ? 0 : -EAGAIN;
 393 }
 394
 395 static void z_erofs_try_to_claim_pcluster(struct z_erofs_collector *clt)
 396 {
 397         struct z_erofs_pcluster *pcl = clt->pcl;
 398         z_erofs_next_pcluster_t *owned_head = &clt->owned_head;
 399
 400         /* type 1, nil pcluster (this pcluster doesn't belong to any chain.) */
 401         if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_NIL,
 402                     *owned_head) == Z_EROFS_PCLUSTER_NIL) {
 403                 *owned_head = &pcl->next;
 404                 /* so we can attach this pcluster to our submission chain. */
 405                 clt->mode = COLLECT_PRIMARY_FOLLOWED;
 406                 return;
 407         }
 408
 409         /*
 410          * type 2, link to the end of an existing open chain, be careful
 411          * that its submission is controlled by the original attached chain.
 412          */
 413         if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
 414                     *owned_head) == Z_EROFS_PCLUSTER_TAIL) {
 415                 *owned_head = Z_EROFS_PCLUSTER_TAIL;
 416                 clt->mode = COLLECT_PRIMARY_HOOKED;
 417                 clt->tailpcl = NULL;
 418                 return;
 419         }
 420         /* type 3, it belongs to a chain, but it isn't the end of the chain */
 421         clt->mode = COLLECT_PRIMARY;
 422 }
 423
 424 static int z_erofs_lookup_collection(struct z_erofs_collector *clt,
 425                                      struct inode *inode,
 426                                      struct erofs_map_blocks *map)
 427 {
 428         struct z_erofs_pcluster *pcl = clt->pcl;
 429         struct z_erofs_collection *cl;
 430         unsigned int length;
 431
 432         /* to avoid unexpected loop formed by corrupted images */
 433         if (clt->owned_head == &pcl->next || pcl == clt->tailpcl) {
 434                 DBG_BUGON(1);
 435                 return -EFSCORRUPTED;
 436         }
 437
 438         cl = z_erofs_primarycollection(pcl);
 439         if (cl->pageofs != (map->m_la & ~PAGE_MASK)) {
 440                 DBG_BUGON(1);
 441                 return -EFSCORRUPTED;
 442         }
 443
 444         length = READ_ONCE(pcl->length);
 445         if (length & Z_EROFS_PCLUSTER_FULL_LENGTH) {
 446                 if ((map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) > length) {
 447                         DBG_BUGON(1);
 448                         return -EFSCORRUPTED;
 449                 }
 450         } else {
 451                 unsigned int llen = map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT;
 452
 453                 if (map->m_flags & EROFS_MAP_FULL_MAPPED)
 454                         llen |= Z_EROFS_PCLUSTER_FULL_LENGTH;
 455
 456                 while (llen > length &&
 457                        length != cmpxchg_relaxed(&pcl->length, length, llen)) {
 458                         cpu_relax();
 459                         length = READ_ONCE(pcl->length);
 460                 }
 461         }
 462         mutex_lock(&cl->lock);
 463         /* used to check tail merging loop due to corrupted images */
 464         if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
 465                 clt->tailpcl = pcl;
 466
 467         z_erofs_try_to_claim_pcluster(clt);
 468         clt->cl = cl;
 469         return 0;
 470 }
 471
 472 static int z_erofs_register_collection(struct z_erofs_collector *clt,
 473                                        struct inode *inode,
 474                                        struct erofs_map_blocks *map)
 475 {
 476         struct z_erofs_pcluster *pcl;
 477         struct z_erofs_collection *cl;
 478         struct erofs_workgroup *grp;
 479         int err;
 480
 481         /* no available pcluster, let's allocate one */
 482         pcl = z_erofs_alloc_pcluster(map->m_plen >> PAGE_SHIFT);
 483         if (IS_ERR(pcl))
 484                 return PTR_ERR(pcl);
 485
 486         atomic_set(&pcl->obj.refcount, 1);
 487         pcl->obj.index = map->m_pa >> PAGE_SHIFT;
 488
 489         pcl->length = (map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) |
 490                 (map->m_flags & EROFS_MAP_FULL_MAPPED ?
 491                         Z_EROFS_PCLUSTER_FULL_LENGTH : 0);
 492
 493         if (map->m_flags & EROFS_MAP_ZIPPED)
 494                 pcl->algorithmformat = Z_EROFS_COMPRESSION_LZ4;
 495         else
 496                 pcl->algorithmformat = Z_EROFS_COMPRESSION_SHIFTED;
 497
 498         /* new pclusters should be claimed as type 1, primary and followed */
 499         pcl->next = clt->owned_head;
 500         clt->mode = COLLECT_PRIMARY_FOLLOWED;
 501
 502         cl = z_erofs_primarycollection(pcl);
 503         cl->pageofs = map->m_la & ~PAGE_MASK;
 504
 505         /*
 506          * lock all primary followed works before visible to others
 507          * and mutex_trylock *never* fails for a new pcluster.
 508          */
 509         mutex_init(&cl->lock);
 510         DBG_BUGON(!mutex_trylock(&cl->lock));
 511
 512         grp = erofs_insert_workgroup(inode->i_sb, &pcl->obj);
 513         if (IS_ERR(grp)) {
 514                 err = PTR_ERR(grp);
 515                 goto err_out;
 516         }
 517
 518         if (grp != &pcl->obj) {
 519                 clt->pcl = container_of(grp, struct z_erofs_pcluster, obj);
 520                 err = -EEXIST;
 521                 goto err_out;
 522         }
 523         /* used to check tail merging loop due to corrupted images */
 524         if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
 525                 clt->tailpcl = pcl;
 526         clt->owned_head = &pcl->next;
 527         clt->pcl = pcl;
 528         clt->cl = cl;
 529         return 0;
 530
 531 err_out:
 532         mutex_unlock(&cl->lock);
 533         z_erofs_free_pcluster(pcl);
 534         return err;
 535 }
 536
 537 static int z_erofs_collector_begin(struct z_erofs_collector *clt,
 538                                    struct inode *inode,
 539                                    struct erofs_map_blocks *map)
 540 {
 541         struct erofs_workgroup *grp;
 542         int ret;
 543
 544         DBG_BUGON(clt->cl);
 545
 546         /* must be Z_EROFS_PCLUSTER_TAIL or pointed to previous collection */
 547         DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_NIL);
 548         DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
 549
 550         if (!PAGE_ALIGNED(map->m_pa)) {
 551                 DBG_BUGON(1);
 552                 return -EINVAL;
 553         }
 554
 555         grp = erofs_find_workgroup(inode->i_sb, map->m_pa >> PAGE_SHIFT);
 556         if (grp) {
 557                 clt->pcl = container_of(grp, struct z_erofs_pcluster, obj);
 558         } else {
 559                 ret = z_erofs_register_collection(clt, inode, map);
 560
 561                 if (!ret)
 562                         goto out;
 563                 if (ret != -EEXIST)
 564                         return ret;
 565         }
 566
 567         ret = z_erofs_lookup_collection(clt, inode, map);
 568         if (ret) {
 569                 erofs_workgroup_put(&clt->pcl->obj);
 570                 return ret;
 571         }
 572
 573 out:
 574         z_erofs_pagevec_ctor_init(&clt->vector, Z_EROFS_NR_INLINE_PAGEVECS,
 575                                   clt->cl->pagevec, clt->cl->vcnt);
 576
 577         /* since file-backed online pages are traversed in reverse order */
 578         clt->icpage_ptr = clt->pcl->compressed_pages + clt->pcl->pclusterpages;
 579         return 0;
 580 }
 581
 582 /*
 583  * keep in mind that no referenced pclusters will be freed
 584  * only after a RCU grace period.
 585  */
 586 static void z_erofs_rcu_callback(struct rcu_head *head)
 587 {
 588         struct z_erofs_collection *const cl =
 589                 container_of(head, struct z_erofs_collection, rcu);
 590
 591         z_erofs_free_pcluster(container_of(cl, struct z_erofs_pcluster,
 592                                            primary_collection));
 593 }
 594
 595 void erofs_workgroup_free_rcu(struct erofs_workgroup *grp)
 596 {
 597         struct z_erofs_pcluster *const pcl =
 598                 container_of(grp, struct z_erofs_pcluster, obj);
 599         struct z_erofs_collection *const cl = z_erofs_primarycollection(pcl);
 600
 601         call_rcu(&cl->rcu, z_erofs_rcu_callback);
 602 }
 603
 604 static void z_erofs_collection_put(struct z_erofs_collection *cl)
 605 {
 606         struct z_erofs_pcluster *const pcl =
 607                 container_of(cl, struct z_erofs_pcluster, primary_collection);
 608
 609         erofs_workgroup_put(&pcl->obj);
 610 }
 611
 612 static bool z_erofs_collector_end(struct z_erofs_collector *clt)
 613 {
 614         struct z_erofs_collection *cl = clt->cl;
 615
 616         if (!cl)
 617                 return false;
 618
 619         z_erofs_pagevec_ctor_exit(&clt->vector, false);
 620         mutex_unlock(&cl->lock);
 621
 622         /*
 623          * if all pending pages are added, don't hold its reference
 624          * any longer if the pcluster isn't hosted by ourselves.
 625          */
 626         if (clt->mode < COLLECT_PRIMARY_FOLLOWED_NOINPLACE)
 627                 z_erofs_collection_put(cl);
 628
 629         clt->cl = NULL;
 630         return true;
 631 }
 632
 633 static bool should_alloc_managed_pages(struct z_erofs_decompress_frontend *fe,
 634                                        unsigned int cachestrategy,
 635                                        erofs_off_t la)
 636 {
 637         if (cachestrategy <= EROFS_ZIP_CACHE_DISABLED)
 638                 return false;
 639
 640         if (fe->backmost)
 641                 return true;
 642
 643         return cachestrategy >= EROFS_ZIP_CACHE_READAROUND &&
 644                 la < fe->headoffset;
 645 }
 646
 647 static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
 648                                 struct page *page, struct list_head *pagepool)
 649 {
 650         struct inode *const inode = fe->inode;
 651         struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
 652         struct erofs_map_blocks *const map = &fe->map;
 653         struct z_erofs_collector *const clt = &fe->clt;
 654         const loff_t offset = page_offset(page);
 655         bool tight = true;
 656
 657         enum z_erofs_cache_alloctype cache_strategy;
 658         enum z_erofs_page_type page_type;
 659         unsigned int cur, end, spiltted, index;
 660         int err = 0;
 661
 662         /* register locked file pages as online pages in pack */
 663         z_erofs_onlinepage_init(page);
 664
 665         spiltted = 0;
 666         end = PAGE_SIZE;
 667 repeat:
 668         cur = end - 1;
 669
 670         /* lucky, within the range of the current map_blocks */
 671         if (offset + cur >= map->m_la &&
 672             offset + cur < map->m_la + map->m_llen) {
 673                 /* didn't get a valid collection previously (very rare) */
 674                 if (!clt->cl)
 675                         goto restart_now;
 676                 goto hitted;
 677         }
 678
 679         /* go ahead the next map_blocks */
 680         erofs_dbg("%s: [out-of-range] pos %llu", __func__, offset + cur);
 681
 682         if (z_erofs_collector_end(clt))
 683                 fe->backmost = false;
 684
 685         map->m_la = offset + cur;
 686         map->m_llen = 0;
 687         err = z_erofs_map_blocks_iter(inode, map, 0);
 688         if (err)
 689                 goto err_out;
 690
 691 restart_now:
 692         if (!(map->m_flags & EROFS_MAP_MAPPED))
 693                 goto hitted;
 694
 695         err = z_erofs_collector_begin(clt, inode, map);
 696         if (err)
 697                 goto err_out;
 698
 699         /* preload all compressed pages (maybe downgrade role if necessary) */
 700         if (should_alloc_managed_pages(fe, sbi->ctx.cache_strategy, map->m_la))
 701                 cache_strategy = TRYALLOC;
 702         else
 703                 cache_strategy = DONTALLOC;
 704
 705         preload_compressed_pages(clt, MNGD_MAPPING(sbi),
 706                                  cache_strategy, pagepool);
 707
 708 hitted:
 709         /*
 710          * Ensure the current partial page belongs to this submit chain rather
 711          * than other concurrent submit chains or the noio(bypass) chain since
 712          * those chains are handled asynchronously thus the page cannot be used
 713          * for inplace I/O or pagevec (should be processed in strict order.)
 714          */
 715         tight &= (clt->mode >= COLLECT_PRIMARY_HOOKED &&
 716                   clt->mode != COLLECT_PRIMARY_FOLLOWED_NOINPLACE);
 717
 718         cur = end - min_t(unsigned int, offset + end - map->m_la, end);
 719         if (!(map->m_flags & EROFS_MAP_MAPPED)) {
 720                 zero_user_segment(page, cur, end);
 721                 goto next_part;
 722         }
 723
 724         /* let's derive page type */
 725         page_type = cur ? Z_EROFS_VLE_PAGE_TYPE_HEAD :
 726                 (!spiltted ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
 727                         (tight ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
 728                                 Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED));
 729
 730         if (cur)
 731                 tight &= (clt->mode >= COLLECT_PRIMARY_FOLLOWED);
 732
 733 retry:
 734         err = z_erofs_attach_page(clt, page, page_type);
 735         /* should allocate an additional short-lived page for pagevec */
 736         if (err == -EAGAIN) {
 737                 struct page *const newpage =
 738                                 alloc_page(GFP_NOFS | __GFP_NOFAIL);
 739
 740                 set_page_private(newpage, Z_EROFS_SHORTLIVED_PAGE);
 741                 err = z_erofs_attach_page(clt, newpage,
 742                                           Z_EROFS_PAGE_TYPE_EXCLUSIVE);
 743                 if (!err)
 744                         goto retry;
 745         }
 746
 747         if (err)
 748                 goto err_out;
 749
 750         index = page->index - (map->m_la >> PAGE_SHIFT);
 751
 752         z_erofs_onlinepage_fixup(page, index, true);
 753
 754         /* bump up the number of spiltted parts of a page */
 755         ++spiltted;
 756         /* also update nr_pages */
 757         clt->cl->nr_pages = max_t(pgoff_t, clt->cl->nr_pages, index + 1);
 758 next_part:
 759         /* can be used for verification */
 760         map->m_llen = offset + cur - map->m_la;
 761
 762         end = cur;
 763         if (end > 0)
 764                 goto repeat;
 765
 766 out:
 767         z_erofs_onlinepage_endio(page);
 768
 769         erofs_dbg("%s, finish page: %pK spiltted: %u map->m_llen %llu",
 770                   __func__, page, spiltted, map->m_llen);
 771         return err;
 772
 773         /* if some error occurred while processing this page */
 774 err_out:
 775         SetPageError(page);
 776         goto out;
 777 }
 778
 779 static void z_erofs_decompressqueue_work(struct work_struct *work);
 780 static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
 781                                        bool sync, int bios)
 782 {
 783         struct erofs_sb_info *const sbi = EROFS_SB(io->sb);
 784
 785         /* wake up the caller thread for sync decompression */
 786         if (sync) {
 787                 unsigned long flags;
 788
 789                 spin_lock_irqsave(&io->u.wait.lock, flags);
 790                 if (!atomic_add_return(bios, &io->pending_bios))
 791                         wake_up_locked(&io->u.wait);
 792                 spin_unlock_irqrestore(&io->u.wait.lock, flags);
 793                 return;
 794         }
 795
 796         if (atomic_add_return(bios, &io->pending_bios))
 797                 return;
 798         /* Use workqueue and sync decompression for atomic contexts only */
 799         if (in_atomic() || irqs_disabled()) {
 800                 queue_work(z_erofs_workqueue, &io->u.work);
 801                 sbi->ctx.readahead_sync_decompress = true;
 802                 return;
 803         }
 804         z_erofs_decompressqueue_work(&io->u.work);
 805 }
 806
 807 static bool z_erofs_page_is_invalidated(struct page *page)
 808 {
 809         return !page->mapping && !z_erofs_is_shortlived_page(page);
 810 }
 811
 812 static void z_erofs_decompressqueue_endio(struct bio *bio)
 813 {
 814         tagptr1_t t = tagptr_init(tagptr1_t, bio->bi_private);
 815         struct z_erofs_decompressqueue *q = tagptr_unfold_ptr(t);
 816         blk_status_t err = bio->bi_status;
 817         struct bio_vec *bvec;
 818         struct bvec_iter_all iter_all;
 819
 820         bio_for_each_segment_all(bvec, bio, iter_all) {
 821                 struct page *page = bvec->bv_page;
 822
 823                 DBG_BUGON(PageUptodate(page));
 824                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 825
 826                 if (err)
 827                         SetPageError(page);
 828
 829                 if (erofs_page_is_managed(EROFS_SB(q->sb), page)) {
 830                         if (!err)
 831                                 SetPageUptodate(page);
 832                         unlock_page(page);
 833                 }
 834         }
 835         z_erofs_decompress_kickoff(q, tagptr_unfold_tags(t), -1);
 836         bio_put(bio);
 837 }
 838
 839 static int z_erofs_decompress_pcluster(struct super_block *sb,
 840                                        struct z_erofs_pcluster *pcl,
 841                                        struct list_head *pagepool)
 842 {
 843         struct erofs_sb_info *const sbi = EROFS_SB(sb);
 844         struct z_erofs_pagevec_ctor ctor;
 845         unsigned int i, inputsize, outputsize, llen, nr_pages;
 846         struct page *pages_onstack[Z_EROFS_VMAP_ONSTACK_PAGES];
 847         struct page **pages, **compressed_pages, *page;
 848
 849         enum z_erofs_page_type page_type;
 850         bool overlapped, partial;
 851         struct z_erofs_collection *cl;
 852         int err;
 853
 854         might_sleep();
 855         cl = z_erofs_primarycollection(pcl);
 856         DBG_BUGON(!READ_ONCE(cl->nr_pages));
 857
 858         mutex_lock(&cl->lock);
 859         nr_pages = cl->nr_pages;
 860
 861         if (nr_pages <= Z_EROFS_VMAP_ONSTACK_PAGES) {
 862                 pages = pages_onstack;
 863         } else if (nr_pages <= Z_EROFS_VMAP_GLOBAL_PAGES &&
 864                    mutex_trylock(&z_pagemap_global_lock)) {
 865                 pages = z_pagemap_global;
 866         } else {
 867                 gfp_t gfp_flags = GFP_KERNEL;
 868
 869                 if (nr_pages > Z_EROFS_VMAP_GLOBAL_PAGES)
 870                         gfp_flags |= __GFP_NOFAIL;
 871
 872                 pages = kvmalloc_array(nr_pages, sizeof(struct page *),
 873                                        gfp_flags);
 874
 875                 /* fallback to global pagemap for the lowmem scenario */
 876                 if (!pages) {
 877                         mutex_lock(&z_pagemap_global_lock);
 878                         pages = z_pagemap_global;
 879                 }
 880         }
 881
 882         for (i = 0; i < nr_pages; ++i)
 883                 pages[i] = NULL;
 884
 885         err = 0;
 886         z_erofs_pagevec_ctor_init(&ctor, Z_EROFS_NR_INLINE_PAGEVECS,
 887                                   cl->pagevec, 0);
 888
 889         for (i = 0; i < cl->vcnt; ++i) {
 890                 unsigned int pagenr;
 891
 892                 page = z_erofs_pagevec_dequeue(&ctor, &page_type);
 893
 894                 /* all pages in pagevec ought to be valid */
 895                 DBG_BUGON(!page);
 896                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 897
 898                 if (z_erofs_put_shortlivedpage(pagepool, page))
 899                         continue;
 900
 901                 if (page_type == Z_EROFS_VLE_PAGE_TYPE_HEAD)
 902                         pagenr = 0;
 903                 else
 904                         pagenr = z_erofs_onlinepage_index(page);
 905
 906                 DBG_BUGON(pagenr >= nr_pages);
 907
 908                 /*
 909                  * currently EROFS doesn't support multiref(dedup),
 910                  * so here erroring out one multiref page.
 911                  */
 912                 if (pages[pagenr]) {
 913                         DBG_BUGON(1);
 914                         SetPageError(pages[pagenr]);
 915                         z_erofs_onlinepage_endio(pages[pagenr]);
 916                         err = -EFSCORRUPTED;
 917                 }
 918                 pages[pagenr] = page;
 919         }
 920         z_erofs_pagevec_ctor_exit(&ctor, true);
 921
 922         overlapped = false;
 923         compressed_pages = pcl->compressed_pages;
 924
 925         for (i = 0; i < pcl->pclusterpages; ++i) {
 926                 unsigned int pagenr;
 927
 928                 page = compressed_pages[i];
 929
 930                 /* all compressed pages ought to be valid */
 931                 DBG_BUGON(!page);
 932                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 933
 934                 if (!z_erofs_is_shortlived_page(page)) {
 935                         if (erofs_page_is_managed(sbi, page)) {
 936                                 if (!PageUptodate(page))
 937                                         err = -EIO;
 938                                 continue;
 939                         }
 940
 941                         /*
 942                          * only if non-head page can be selected
 943                          * for inplace decompression
 944                          */
 945                         pagenr = z_erofs_onlinepage_index(page);
 946
 947                         DBG_BUGON(pagenr >= nr_pages);
 948                         if (pages[pagenr]) {
 949                                 DBG_BUGON(1);
 950                                 SetPageError(pages[pagenr]);
 951                                 z_erofs_onlinepage_endio(pages[pagenr]);
 952                                 err = -EFSCORRUPTED;
 953                         }
 954                         pages[pagenr] = page;
 955
 956                         overlapped = true;
 957                 }
 958
 959                 /* PG_error needs checking for all non-managed pages */
 960                 if (PageError(page)) {
 961                         DBG_BUGON(PageUptodate(page));
 962                         err = -EIO;
 963                 }
 964         }
 965
 966         if (err)
 967                 goto out;
 968
 969         llen = pcl->length >> Z_EROFS_PCLUSTER_LENGTH_BIT;
 970         if (nr_pages << PAGE_SHIFT >= cl->pageofs + llen) {
 971                 outputsize = llen;
 972                 partial = !(pcl->length & Z_EROFS_PCLUSTER_FULL_LENGTH);
 973         } else {
 974                 outputsize = (nr_pages << PAGE_SHIFT) - cl->pageofs;
 975                 partial = true;
 976         }
 977
 978         inputsize = pcl->pclusterpages * PAGE_SIZE;
 979         err = z_erofs_decompress(&(struct z_erofs_decompress_req) {
 980                                         .sb = sb,
 981                                         .in = compressed_pages,
 982                                         .out = pages,
 983                                         .pageofs_out = cl->pageofs,
 984                                         .inputsize = inputsize,
 985                                         .outputsize = outputsize,
 986                                         .alg = pcl->algorithmformat,
 987                                         .inplace_io = overlapped,
 988                                         .partial_decoding = partial
 989                                  }, pagepool);
 990
 991 out:
 992         /* must handle all compressed pages before ending pages */
 993         for (i = 0; i < pcl->pclusterpages; ++i) {
 994                 page = compressed_pages[i];
 995
 996                 if (erofs_page_is_managed(sbi, page))
 997                         continue;
 998
 999                 /* recycle all individual short-lived pages */
1000                 (void)z_erofs_put_shortlivedpage(pagepool, page);
1001
1002                 WRITE_ONCE(compressed_pages[i], NULL);
1003         }
1004
1005         for (i = 0; i < nr_pages; ++i) {
1006                 page = pages[i];
1007                 if (!page)
1008                         continue;
1009
1010                 DBG_BUGON(z_erofs_page_is_invalidated(page));
1011
1012                 /* recycle all individual short-lived pages */
1013                 if (z_erofs_put_shortlivedpage(pagepool, page))
1014                         continue;
1015
1016                 if (err < 0)
1017                         SetPageError(page);
1018
1019                 z_erofs_onlinepage_endio(page);
1020         }
1021
1022         if (pages == z_pagemap_global)
1023                 mutex_unlock(&z_pagemap_global_lock);
1024         else if (pages != pages_onstack)
1025                 kvfree(pages);
1026
1027         cl->nr_pages = 0;
1028         cl->vcnt = 0;
1029
1030         /* all cl locks MUST be taken before the following line */
1031         WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_NIL);
1032
1033         /* all cl locks SHOULD be released right now */
1034         mutex_unlock(&cl->lock);
1035
1036         z_erofs_collection_put(cl);
1037         return err;
1038 }
1039
1040 static void z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io,
1041                                      struct list_head *pagepool)
1042 {
1043         z_erofs_next_pcluster_t owned = io->head;
1044
1045         while (owned != Z_EROFS_PCLUSTER_TAIL_CLOSED) {
1046                 struct z_erofs_pcluster *pcl;
1047
1048                 /* no possible that 'owned' equals Z_EROFS_WORK_TPTR_TAIL */
1049                 DBG_BUGON(owned == Z_EROFS_PCLUSTER_TAIL);
1050
1051                 /* no possible that 'owned' equals NULL */
1052                 DBG_BUGON(owned == Z_EROFS_PCLUSTER_NIL);
1053
1054                 pcl = container_of(owned, struct z_erofs_pcluster, next);
1055                 owned = READ_ONCE(pcl->next);
1056
1057                 z_erofs_decompress_pcluster(io->sb, pcl, pagepool);
1058         }
1059 }
1060
1061 static void z_erofs_decompressqueue_work(struct work_struct *work)
1062 {
1063         struct z_erofs_decompressqueue *bgq =
1064                 container_of(work, struct z_erofs_decompressqueue, u.work);
1065         LIST_HEAD(pagepool);
1066
1067         DBG_BUGON(bgq->head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1068         z_erofs_decompress_queue(bgq, &pagepool);
1069
1070         put_pages_list(&pagepool);
1071         kvfree(bgq);
1072 }
1073
1074 static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl,
1075                                                unsigned int nr,
1076                                                struct list_head *pagepool,
1077                                                struct address_space *mc,
1078                                                gfp_t gfp)
1079 {
1080         const pgoff_t index = pcl->obj.index;
1081         bool tocache = false;
1082
1083         struct address_space *mapping;
1084         struct page *oldpage, *page;
1085
1086         compressed_page_t t;
1087         int justfound;
1088
1089 repeat:
1090         page = READ_ONCE(pcl->compressed_pages[nr]);
1091         oldpage = page;
1092
1093         if (!page)
1094                 goto out_allocpage;
1095
1096         /*
1097          * the cached page has not been allocated and
1098          * an placeholder is out there, prepare it now.
1099          */
1100         if (page == PAGE_UNALLOCATED) {
1101                 tocache = true;
1102                 goto out_allocpage;
1103         }
1104
1105         /* process the target tagged pointer */
1106         t = tagptr_init(compressed_page_t, page);
1107         justfound = tagptr_unfold_tags(t);
1108         page = tagptr_unfold_ptr(t);
1109
1110         /*
1111          * preallocated cached pages, which is used to avoid direct reclaim
1112          * otherwise, it will go inplace I/O path instead.
1113          */
1114         if (page->private == Z_EROFS_PREALLOCATED_PAGE) {
1115                 WRITE_ONCE(pcl->compressed_pages[nr], page);
1116                 set_page_private(page, 0);
1117                 tocache = true;
1118                 goto out_tocache;
1119         }
1120         mapping = READ_ONCE(page->mapping);
1121
1122         /*
1123          * file-backed online pages in plcuster are all locked steady,
1124          * therefore it is impossible for `mapping' to be NULL.
1125          */
1126         if (mapping && mapping != mc)
1127                 /* ought to be unmanaged pages */
1128                 goto out;
1129
1130         /* directly return for shortlived page as well */
1131         if (z_erofs_is_shortlived_page(page))
1132                 goto out;
1133
1134         lock_page(page);
1135
1136         /* only true if page reclaim goes wrong, should never happen */
1137         DBG_BUGON(justfound && PagePrivate(page));
1138
1139         /* the page is still in manage cache */
1140         if (page->mapping == mc) {
1141                 WRITE_ONCE(pcl->compressed_pages[nr], page);
1142
1143                 ClearPageError(page);
1144                 if (!PagePrivate(page)) {
1145                         /*
1146                          * impossible to be !PagePrivate(page) for
1147                          * the current restriction as well if
1148                          * the page is already in compressed_pages[].
1149                          */
1150                         DBG_BUGON(!justfound);
1151
1152                         justfound = 0;
1153                         set_page_private(page, (unsigned long)pcl);
1154                         SetPagePrivate(page);
1155                 }
1156
1157                 /* no need to submit io if it is already up-to-date */
1158                 if (PageUptodate(page)) {
1159                         unlock_page(page);
1160                         page = NULL;
1161                 }
1162                 goto out;
1163         }
1164
1165         /*
1166          * the managed page has been truncated, it's unsafe to
1167          * reuse this one, let's allocate a new cache-managed page.
1168          */
1169         DBG_BUGON(page->mapping);
1170         DBG_BUGON(!justfound);
1171
1172         tocache = true;
1173         unlock_page(page);
1174         put_page(page);
1175 out_allocpage:
1176         page = erofs_allocpage(pagepool, gfp | __GFP_NOFAIL);
1177         if (oldpage != cmpxchg(&pcl->compressed_pages[nr], oldpage, page)) {
1178                 list_add(&page->lru, pagepool);
1179                 cond_resched();
1180                 goto repeat;
1181         }
1182 out_tocache:
1183         if (!tocache || add_to_page_cache_lru(page, mc, index + nr, gfp)) {
1184                 /* turn into temporary page if fails (1 ref) */
1185                 set_page_private(page, Z_EROFS_SHORTLIVED_PAGE);
1186                 goto out;
1187         }
1188         attach_page_private(page, pcl);
1189         /* drop a refcount added by allocpage (then we have 2 refs here) */
1190         put_page(page);
1191
1192 out:    /* the only exit (for tracing and debugging) */
1193         return page;
1194 }
1195
1196 static struct z_erofs_decompressqueue *
1197 jobqueue_init(struct super_block *sb,
1198               struct z_erofs_decompressqueue *fgq, bool *fg)
1199 {
1200         struct z_erofs_decompressqueue *q;
1201
1202         if (fg && !*fg) {
1203                 q = kvzalloc(sizeof(*q), GFP_KERNEL | __GFP_NOWARN);
1204                 if (!q) {
1205                         *fg = true;
1206                         goto fg_out;
1207                 }
1208                 INIT_WORK(&q->u.work, z_erofs_decompressqueue_work);
1209         } else {
1210 fg_out:
1211                 q = fgq;
1212                 init_waitqueue_head(&fgq->u.wait);
1213                 atomic_set(&fgq->pending_bios, 0);
1214         }
1215         q->sb = sb;
1216         q->head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
1217         return q;
1218 }
1219
1220 /* define decompression jobqueue types */
1221 enum {
1222         JQ_BYPASS,
1223         JQ_SUBMIT,
1224         NR_JOBQUEUES,
1225 };
1226
1227 static void *jobqueueset_init(struct super_block *sb,
1228                               struct z_erofs_decompressqueue *q[],
1229                               struct z_erofs_decompressqueue *fgq, bool *fg)
1230 {
1231         /*
1232          * if managed cache is enabled, bypass jobqueue is needed,
1233          * no need to read from device for all pclusters in this queue.
1234          */
1235         q[JQ_BYPASS] = jobqueue_init(sb, fgq + JQ_BYPASS, NULL);
1236         q[JQ_SUBMIT] = jobqueue_init(sb, fgq + JQ_SUBMIT, fg);
1237
1238         return tagptr_cast_ptr(tagptr_fold(tagptr1_t, q[JQ_SUBMIT], *fg));
1239 }
1240
1241 static void move_to_bypass_jobqueue(struct z_erofs_pcluster *pcl,
1242                                     z_erofs_next_pcluster_t qtail[],
1243                                     z_erofs_next_pcluster_t owned_head)
1244 {
1245         z_erofs_next_pcluster_t *const submit_qtail = qtail[JQ_SUBMIT];
1246         z_erofs_next_pcluster_t *const bypass_qtail = qtail[JQ_BYPASS];
1247
1248         DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1249         if (owned_head == Z_EROFS_PCLUSTER_TAIL)
1250                 owned_head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
1251
1252         WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_TAIL_CLOSED);
1253
1254         WRITE_ONCE(*submit_qtail, owned_head);
1255         WRITE_ONCE(*bypass_qtail, &pcl->next);
1256
1257         qtail[JQ_BYPASS] = &pcl->next;
1258 }
1259
1260 static void z_erofs_submit_queue(struct super_block *sb,
1261                                  struct z_erofs_decompress_frontend *f,
1262                                  struct list_head *pagepool,
1263                                  struct z_erofs_decompressqueue *fgq,
1264                                  bool *force_fg)
1265 {
1266         struct erofs_sb_info *const sbi = EROFS_SB(sb);
1267         z_erofs_next_pcluster_t qtail[NR_JOBQUEUES];
1268         struct z_erofs_decompressqueue *q[NR_JOBQUEUES];
1269         void *bi_private;
1270         z_erofs_next_pcluster_t owned_head = f->clt.owned_head;
1271         /* since bio will be NULL, no need to initialize last_index */
1272         pgoff_t last_index;
1273         unsigned int nr_bios = 0;
1274         struct bio *bio = NULL;
1275
1276         bi_private = jobqueueset_init(sb, q, fgq, force_fg);
1277         qtail[JQ_BYPASS] = &q[JQ_BYPASS]->head;
1278         qtail[JQ_SUBMIT] = &q[JQ_SUBMIT]->head;
1279
1280         /* by default, all need io submission */
1281         q[JQ_SUBMIT]->head = owned_head;
1282
1283         do {
1284                 struct z_erofs_pcluster *pcl;
1285                 pgoff_t cur, end;
1286                 unsigned int i = 0;
1287                 bool bypass = true;
1288
1289                 /* no possible 'owned_head' equals the following */
1290                 DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1291                 DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_NIL);
1292
1293                 pcl = container_of(owned_head, struct z_erofs_pcluster, next);
1294
1295                 cur = pcl->obj.index;
1296                 end = cur + pcl->pclusterpages;
1297
1298                 /* close the main owned chain at first */
1299                 owned_head = cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
1300                                      Z_EROFS_PCLUSTER_TAIL_CLOSED);
1301
1302                 do {
1303                         struct page *page;
1304
1305                         page = pickup_page_for_submission(pcl, i++, pagepool,
1306                                                           MNGD_MAPPING(sbi),
1307                                                           GFP_NOFS);
1308                         if (!page)
1309                                 continue;
1310
1311                         if (bio && cur != last_index + 1) {
1312 submit_bio_retry:
1313                                 submit_bio(bio);
1314                                 bio = NULL;
1315                         }
1316
1317                         if (!bio) {
1318                                 bio = bio_alloc(GFP_NOIO, BIO_MAX_VECS);
1319
1320                                 bio->bi_end_io = z_erofs_decompressqueue_endio;
1321                                 bio_set_dev(bio, sb->s_bdev);
1322                                 bio->bi_iter.bi_sector = (sector_t)cur <<
1323                                         LOG_SECTORS_PER_BLOCK;
1324                                 bio->bi_private = bi_private;
1325                                 bio->bi_opf = REQ_OP_READ;
1326                                 if (f->readahead)
1327                                         bio->bi_opf |= REQ_RAHEAD;
1328                                 ++nr_bios;
1329                         }
1330
1331                         if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE)
1332                                 goto submit_bio_retry;
1333
1334                         last_index = cur;
1335                         bypass = false;
1336                 } while (++cur < end);
1337
1338                 if (!bypass)
1339                         qtail[JQ_SUBMIT] = &pcl->next;
1340                 else
1341                         move_to_bypass_jobqueue(pcl, qtail, owned_head);
1342         } while (owned_head != Z_EROFS_PCLUSTER_TAIL);
1343
1344         if (bio)
1345                 submit_bio(bio);
1346
1347         /*
1348          * although background is preferred, no one is pending for submission.
1349          * don't issue workqueue for decompression but drop it directly instead.
1350          */
1351         if (!*force_fg && !nr_bios) {
1352                 kvfree(q[JQ_SUBMIT]);
1353                 return;
1354         }
1355         z_erofs_decompress_kickoff(q[JQ_SUBMIT], *force_fg, nr_bios);
1356 }
1357
1358 static void z_erofs_runqueue(struct super_block *sb,
1359                              struct z_erofs_decompress_frontend *f,
1360                              struct list_head *pagepool, bool force_fg)
1361 {
1362         struct z_erofs_decompressqueue io[NR_JOBQUEUES];
1363
1364         if (f->clt.owned_head == Z_EROFS_PCLUSTER_TAIL)
1365                 return;
1366         z_erofs_submit_queue(sb, f, pagepool, io, &force_fg);
1367
1368         /* handle bypass queue (no i/o pclusters) immediately */
1369         z_erofs_decompress_queue(&io[JQ_BYPASS], pagepool);
1370
1371         if (!force_fg)
1372                 return;
1373
1374         /* wait until all bios are completed */
1375         io_wait_event(io[JQ_SUBMIT].u.wait,
1376                       !atomic_read(&io[JQ_SUBMIT].pending_bios));
1377
1378         /* handle synchronous decompress queue in the caller context */
1379         z_erofs_decompress_queue(&io[JQ_SUBMIT], pagepool);
1380 }
1381
1382 static int z_erofs_readpage(struct file *file, struct page *page)
1383 {
1384         struct inode *const inode = page->mapping->host;
1385         struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
1386         int err;
1387         LIST_HEAD(pagepool);
1388
1389         trace_erofs_readpage(page, false);
1390
1391         f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
1392
1393         err = z_erofs_do_read_page(&f, page, &pagepool);
1394         (void)z_erofs_collector_end(&f.clt);
1395
1396         /* if some compressed cluster ready, need submit them anyway */
1397         z_erofs_runqueue(inode->i_sb, &f, &pagepool, true);
1398
1399         if (err)
1400                 erofs_err(inode->i_sb, "failed to read, err [%d]", err);
1401
1402         if (f.map.mpage)
1403                 put_page(f.map.mpage);
1404
1405         /* clean up the remaining free pages */
1406         put_pages_list(&pagepool);
1407         return err;
1408 }
1409
1410 static void z_erofs_readahead(struct readahead_control *rac)
1411 {
1412         struct inode *const inode = rac->mapping->host;
1413         struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
1414
1415         unsigned int nr_pages = readahead_count(rac);
1416         bool sync = (sbi->ctx.readahead_sync_decompress &&
1417                         nr_pages <= sbi->ctx.max_sync_decompress_pages);
1418         struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
1419         struct page *page, *head = NULL;
1420         LIST_HEAD(pagepool);
1421
1422         trace_erofs_readpages(inode, readahead_index(rac), nr_pages, false);
1423
1424         f.readahead = true;
1425         f.headoffset = readahead_pos(rac);
1426
1427         while ((page = readahead_page(rac))) {
1428                 prefetchw(&page->flags);
1429
1430                 /*
1431                  * A pure asynchronous readahead is indicated if
1432                  * a PG_readahead marked page is hitted at first.
1433                  * Let's also do asynchronous decompression for this case.
1434                  */
1435                 sync &= !(PageReadahead(page) && !head);
1436
1437                 set_page_private(page, (unsigned long)head);
1438                 head = page;
1439         }
1440
1441         while (head) {
1442                 struct page *page = head;
1443                 int err;
1444
1445                 /* traversal in reverse order */
1446                 head = (void *)page_private(page);
1447
1448                 err = z_erofs_do_read_page(&f, page, &pagepool);
1449                 if (err)
1450                         erofs_err(inode->i_sb,
1451                                   "readahead error at page %lu @ nid %llu",
1452                                   page->index, EROFS_I(inode)->nid);
1453                 put_page(page);
1454         }
1455
1456         (void)z_erofs_collector_end(&f.clt);
1457
1458         z_erofs_runqueue(inode->i_sb, &f, &pagepool, sync);
1459
1460         if (f.map.mpage)
1461                 put_page(f.map.mpage);
1462
1463         /* clean up the remaining free pages */
1464         put_pages_list(&pagepool);
1465 }
1466
1467 const struct address_space_operations z_erofs_aops = {
1468         .readpage = z_erofs_readpage,
1469         .readahead = z_erofs_readahead,
1470 };